The goal of this project is to define and understand the process by which colon cancer develops and spreads throughout body. The human colon carcinoma cell line, HT-29, was found to consistently metastasize to the liver, pancreas, and peritoneal lymph nodes when injected either subcutaneously or intraperitoneally into nude mice. With decreasing amounts of tumor cells injected s.q., the size of the primary tumor decreased, but rate of metastasis did not, to the point where several animals without evidence of primary tumor had pancreatic metastases. Cells recultured from lung, liver, and lymph node metastases recycled several times through nude mice did not show any evidence of increased metastatic potential. The recycled cells also showed no change in CEA epitopes or in framework HLA distributions. Thus, metastases in this model may not be due to subpopulations of cells, but may reflect a much more complex, dynamically varying process. Metastatic lesions were stained with a variety of monoclonal antibodies and were found to contain both carcinoembryonic antigen and TAG-72. Thus, this model may prove useful in evaluating the use of monoclonal antibodies for diagnosis and therapy. Of interest was the discovery that WiDr is a derivative of HT-29; WiDr, however, is much less metastatic than HT-29 even though it produces more epitopes. Two-dimensional protein analyses of HT-29 and WiDr reveal some proteins absent in one cell but present in the other. Since metastases result from unregulated growth, studies to examine the relationship of cyclin metabolism in each of the two cell lines have been started.